Propylene/propylene/olefin block copolymer and process for producing the same

ABSTRACT

A process for producing a propylene//propylene/olefin block copolymer, characterized by using as a supported metallocene catalyst a solid product obtained by conducting, in this order, the step (a) of reacting an organic transition metal compound having two crosslinked conjugated π-electron ligands with an aluminoxane in an inert solvent, the step (b) of contacting the reaction product obtained in the step (a) with a finely particulate inorganic support in the presence of an inert solvent at 85 to 150° C., and the step (c) of washing the slurry containing a solid product yielded in the step (b) with an aliphatic hydrocarbon at least twice at −50 to 50° C.; and a propylene//propylene/olefin block copolymer produced by said process.

TECHNICAL FIELD

This invention relates to processes for producingpropylene//propylene/olefin block copolymers andpropylene/propylene/olefin block copolymers produced thereby. Moreparticularly, the invention relates to processes for producingpropylene//propylene/olefin block copolymers which comprise a segment Acomprising a polymer based on propylene and a segment B comprising apropylene/olefin random copolymer and have improved bulk density,particle morphology, impact resistance, stiffness and transparency,using a catalyst system for an olefin polymerization comprising as amain component a metallocene catalyst having an enhanced polymerizationactivity, and propylene//propylene/olefin block copolymers producedusing the catalyst system.

BACKGROUND ART

Propylene//propylene/olefin block copolymers comprising a polymersegment based on propylene and a propylene/olefin random copolymersegment are excellent in stiffness and impact resistance, and have beenused as propylene type copolymers for various moldings in the fields ofautomobiles, electric home appliances, large size sundry goods or thelike.

Such propylene//propylene/olefin block copolymers have been produced bypolymerizing propylene with propylene and other olefin(s) than propylenein the presence of a catalyst system which comprises an inorganictransition metal compound catalyst having titanium trichloride, titaniumtetrachloride or the mixture thereof supported on a support such asmagnesium chloride or the like, in combination with an organoaluminumcompound, what is called a Ziegler-Natta catalyst system.

In recent years, many processes of producing propylene//propylene/olefinblock copolymers have been proposed which comprise using metallocenecatalyst systems comprising an organic transition metal compound havingat least one π-electron conjugated ligand, i.e., a metallocene compoundin combination with aluminoxane, in place of prior Ziegler-Nattacatalyst system. Propylene//propylene/olefin block copolymers producedusing these metallocene catalyst systems have various expected uses,because of the balance of stiffness and impact resistance being moreimproved than block copolymers produced using prior Ziegler-Nattacatalyst system.

JPA-4-337308 discloses a process for the production of apropylene//propylene/olefin block copolymer which comprises polymerizingpropylene alone or a propylene/ethylene mixture containing up to 6% byweight of ethylene, followed by copolymerizing so as to provide a weightratio of ethylene units/propylene units in the polymer chain being from10/90 to 95/5, in the presence of a homogeneous catalyst systemcomprising a cyclopentadienyl group-containing transition metal compoundrepresented by a specific formula and an organoaluminum compound.JPA-5-202152 and JPA-6-206921 disclose processes for the production ofpolypropylene molding materials wherein a liquid propylene ispolymerized in the first stage in the presence of a homogeneous catalystsystem comprising an indenyl group-containing transition metal compoundrepresented by a specific formula and an organoaluminum compound, toproduce a crystalline polymer containing at least 95% by weight ofpolypropylene, and in the second stage propylene and ethylene arecopolymerized in solution or in suspension (JPA-5-202152) and in gasphase (JPA-6-206921) in the presence of ethylene, to produce anon-crystalline ethylene/propylene copolymer containing 20-90% by weightof ethylene.

JPA-8-92337 discloses a block copolymer comprising a propylene polymerblock with a propylene content of 100-80% by weight and an ethylenecontent of 0-20% by weight, and a copolymer block with a propylenecontent of 0-99.9% by weight, an ethylene content of 99.99-0.09% byweight and a polymerizable polyene compound of 0.01-60% by weight. Theblock copolymer is produced by carrying out the sequential steps offorming the propylene polymer block and forming the copolymer block, inthe presence of a homogeneous catalyst system which comprises atransition metal compound catalyst including an inorganic titaniumcompound and various metallocene compounds and also a compound whichreacts with the transition metal compound to form an ion complex, or ahomogeneous catalyst system wherein an organometallic compound includingan organoaluminum compound is further incorporated in said catalystsystem.

JPA-9-316147 discloses a propylene//ethylene/α-olefin block copolymerwherein a polypropylene component and a copolymer component ofethylene/α-olefin of C₄ or more are block-copolymerized. The blockcopolymer is produced by polymerizing the polypropylene component andthe ethylene/α-olefin copolymer component in the presence of ahomogeneous catalyst system which comprises a transition metal compoundhaving a cyclopentadienyl ring, in combination with at least onecompound selected from aluminoxane, a compound which reacts with thetransition metal compound to form a stable anion and an organoaluminumcompound.

JPA-6-287257 discloses a propylene//propylene/ethylene block copolymerproduced by a process wherein propylene alone or propylene and ethyleneare polymerized in the first stage under the condition of a propyleneconcentration in gas phase being 90 mol % or more, and in the secondstage propylene and ethylene are copolymerized under the condition of apropylene concentration being less than 90 mol %, in the presence of acatalyst system which comprises a metallocene type transition metalcompound, a product prepared by contacting clay, a clay mineral or anion-exchange lamellar compound and an organoaluminum compound, and ifnecessary an organoaluminum compound.

JPA-6-172414 discloses a process for the production of apropylene//propylene/ethylene block copolymer which comprises carryingout a first polymerization wherein propylene alone or propylene andethylene are polymerized in substantially gas phase in the presence of acatalyst system having a cyclopentadienyl ring-containing transitionmetal compound of a specific formula and aluminoxane supported on anorganic porous polymer support, to produce a crystalline homopolymer ofpropylene or a copolymer of propylene and ethylene with an ethylenecontent of 5% by weight or less, and a second polymerization whereinpropylene, ethylene and at least one comonomer selected from α-olefinsof C₄-C₂₀ are copolymerized so as to provide a polymerization molarratio of propylene/comonomer being from 0/100 to 80/20.

JPA-8-27237 discloses a process of producing anethylene/propylene//propylene copolymer which comprises carrying out thepolymerization step (1) wherein propylene and at least one comonomerselected from ethylene and α-olefins of C₄-C₂₀ are copolymerized so thata polymerization ratio in a molar ratio of propylene/comonomer will bein the range from 0/100 to 80/20, in the presence of at least onecompound selected from a transition metal compound having a π-conjugated5-membered ring ligand, aluminoxane, a reaction product of a boroncompound and an organoaluminum compound, a Lewis acid and an ioniccompound, more specifically a catalyst system having an indenyl serieszirconocene and aluminoxane supported on a porous polypropylene support,and then carrying out the polymerization step (2) in the presence of theabove catalyst and the polymer prepared in (1) to produce a crystallinepropylene homopolymer or a propylene copolymer of propylene with atleast one comonomer selected from ethylene and α-olefins of C₄-C₂₀, thecopolymer having a comonomer content of 10% by weight or less.

The above-described references state that thepropylene//propylene/olefin block copolymers produced therein havewell-balanced stiffness and impact resistance at ordinary temperatureand low temperature, the stiffness being evaluated by flexural modulus,etc., and the impact resistance being evaluated by Izod impact strength,etc.

JPA-6-172414 and JPA-8-27237 state that the block copolymers producedtherein are improved in particle morphology and bulk density.

Of the above-described techniques, the technique using the homogeneouscatalyst is applicable to a solution polymerization process, whenindustrial production of a propylene//propylene/olefin block copolymeris taken into consideration. However, the application of this techniqueto a gas phase polymerization process and a slurry polymerizationprocess produces finely divided polymers having an extremely low bulkdensity. Accordingly, industrial production of apropylene//propylene/olefin block copolymer by both processes isdifficult practically. In the process using a supported metallocenecatalyst, a polymerization activity of the catalyst improves to someextent, the amount of aluminoxane used as a cocatalyst is reduced, andan improvement in bulk density and particle morphology of the resultantblock copolymer is secured. However, further improvement in every aspecthas been desired. When an application to a gas phase polymerization isespecially taken into consideration, further improvements inpolymerization activity of the catalyst, bulk density and particlemorphology of the resultant copolymer are demanded.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a process for producinga propylene//propylene/olefin block copolymer, which improves apolymerization activity of the catalyst, can reduce the amount ofaluminoxane used and produces the block copolymer having improved bulkdensity and particle morphology, and further, excellent impact strength,stiffness and transparency, and also to provide thepropylene//propylene/olefin block copolymer produced by said process.

The present inventors have investigated zealously in an effort toachieve the above object, and found that the use of a catalyst systemcomprising a specific supported metallocene catalyst and anorganoaluminum compound in the two-stage polymerization process of apropylene//propylene/olefin as disclosed in the above references canimprove the polymerization activity of the catalyst, and can produce thepropylene//propylene/olefin block copolymer having improved bulk densityand particle morphology, and further, excellent impact strength,stiffness and transparency, thus leading to completion of the presentinvention.

The present invention provides a process for producing apropylene//propylene/olefin block copolymer which comprises 20-95% byweight of segment A comprising a polymer based on propylene and 80-5% byweight of segment B comprising a propylene/olefin random copolymer,characterized by carrying out in sequence the following steps (A) and(B):

(A) a first polymerization step wherein propylene or a mixture ofpropylene and other olefin(s) than propylene is polymerized in thepresence of a catalyst system for olefin polymerization comprising asupported metallocene catalyst and an organoaluminum compound, toproduce the segment A comprising a polymer based on propylene wherein aweight ratio of units of other olefin(s) than propylene/units ofpropylene in the polymer chain is from 0/100 to 30/70, and

(B) a second polymerization step wherein a mixture of propylene,andother olefin(s) than propylene is copolymerized in the presence of thepolymer based on propylene containing the catalyst system for olefinpolymerization from the first polymerization step, to produce thesegment B comprising the propylene/olefin random copolymer wherein aweight ratio of units of propylene/units of other olefin(s) thanpropylene in the polymer chain is from 5/95 to 95/5,

the supported metallocene catalyst comprising a solid product which isprepared by carrying out in sequence the following steps of:

(a) reacting an aluminoxane with an organic transition metal compoundhaving two π-electron conjugated ligands crosslinked each other in aninert solvent,

(b) contacting a reaction product formed in step (a) with an inorganicfinely particulate support in an inert solvent at a temperature of85-150° C., and

(c) washing at least two times a slurry containing the solid productformed in step (b) with an aliphatic hydrocarbon at a temperature of −50to 50° C. The invention also provides the propylene//propylene/olefinblock copolymer produced by said process.

Another aspect of the present invention is a process for producing thepropylene//propylene/olefin block copolymer in the presence of apreactivated catalyst, instead of the supported metallocene catalyst,and also the propylene//propylene/olefin block copolymer produced bysaid process, the preactivated catalyst being characterized bycomprising a granular product which is prepared by carrying out,subsequent to the above step (c), further step (d) wherein the supportedmetallocene catalyst prepared in step (c) is contacted with olefin(s) toprepolymerize the olefin(s) and 0.01-100 kg of the olefin prepolymer perkg of the supported metallocene catalyst is further supported.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is IR absorption spectrum of the supported metallocene catalystused in the present invention.

FIG. 2 is a flow sheet illustrating the process for the production ofthe propylene//propylene/olefin block copolymer according to the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is described in detail below.

In the present invention, the propylene//propylene/olefin blockcopolymers comprise the segment A comprising a polymer based onpropylene which is a propylene homopolymer or a propylene/olefin randomcopolymer wherein a weight ratio of units of other olefin(s) thanpropylene/units of propylene in the polymer chain is from 0/100 to 30/70and the segment B comprising a propylene/olefin random copolymer whereina weight ratio of units of other olefin(s) than propylene/units ofpropylene in the polymer chain is from 5/95 to 95/5, and they include aAB block copolymer wherein segment A and segment B are bonded by acovalent bond, a weight ratio of segment A/segment B being in the rangeof 20/80 to 95/5, a polymer blend wherein a chemical bond may existbetween segment A and segment B, and the mixture thereof.

Other olefins than propylene as described above include straight-chainmonoolefins such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene,1-decene, 1-dodecene or the like; branched-chain monoolefins such as3-methyl-1-butene, 4-methyl-1-pentene, 2-methyl-1-pentene or the like;cyclic olefins such as cyclopentene, cyclohexene, norbornene,5-methyl-2-norbornene, 5-ethyl-2-norbornene, phenylnorbornene,indanylnorbornene or the like; chain polyenes such as 1,3-butadiene,isoprene, 1,4-hexadiene, 1,7-octadiene, 1,9-decadiene,4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 7-methyl-1,6-octadieneor the like; cyclic polyenes such as dicyclopentadiene,5-methylene-2-norbornene, 5-ethylidene-2-norbornene or the like;styrenes such as styrene, vinylnaphthalene, α-methylstyrene or the like;substituted olefins and polyene derivatives such as5-(N,N-diisopropylamino)-1-pentene, 4-trimethylsiloxy-1,6-heptadiene orthe like; and vinyl compounds copolymerizable with an olefin such asvinylcyclohexane, vinyl chloride, methyl methacrylate, ethyl acrylate orthe like. Of these olefins, ethylene and/or 1-butene is most preferablyused.

In the present invention, segment A comprising a polymer based onpropylene mainly gives stiffness to the propylene//propylene/olefinblock copolymer, and segment B comprising a propylene/olefin randomcopolymer mainly gives impact resistance to the block copolymer.

Further, it is important to produce segment A having good particlemorphology in the first polymerization step for the production of thepropylene//propylene/olefin block copolymer having good particlemorphology, by which manufacture of segment B is attained. Then, aweight ratio of units of other olefin(s) than propylene/units ofpropylene in both segments A and B and a weight ratio of both segments Aand B are decided, taking both physical property and particle morphologyof the polymer into consideration.

For imparting high stiffness to the propylene//propylene/olefin blockcopolymer, segment A is a polymer based on propylene comprising apropylene homopolymer or a propylene/olefin (other than propylene)random copolymer, preferably a propylene homopolymer or apropylene/ethylene random copolymer, wherein a weight ratio of units ofother olefin(s) than propylene/units of propylene in the polymer chainis from 0/100 to 30/70, preferably 0/100 to 10/90, more preferably 0/100to 5/95 and most preferably 0/100 to 3/97. More flexible polymer isdemanded depending on the use. In that case, the content of otherolefin(s) than propylene in the random copolymer of propylene/otherolefin(s) than propylene which constitutes segment A is preferably asmuch as possible within the above range, preferably 3 to 20% by weight,taking the physical property and particle morphology of the polymer intoconsideration.

For imparting impact-resistance, especially impact-resistance at lowtemperature to the propylene//propylene/olefin block copolymer, it ispreferable that segment B comprises a propylene/olefin random copolymerwherein a weight ratio of units of other olefin(s) than propylene/unitsof propylene in the polymer chain is from 5/95 to 95/5, preferably 20/80to 75/25, and more preferably 25/75 to 65/35. Preferable other olefinsthan propylene are straight-chain monoolefins and diolefins as recitedabove. In particular, ethylene, butene-1 or the mixture thereof ispreferable.

In view of a balance of stiffness and impact-resistance of thepropylene//propylene/olefin block copolymer, a weight ratio of segmentA/segment B is in the range of 20/80 to 95/5, preferably 20/80 to 80/20and more preferably 20/80 to 70/30. For preparing the polymer of higherstiffness in the range not impairing the impact-resistance, the weightratio is preferably in the range of 85/15 to 95/5. For preparing moreflexible polymer, the weight ratio is preferably in the range of 20/80tO 60/40.

In case where a stress-whitening resistance on impacting,stress-whitening resistance on bending or reduction of mold shrinkagefactor is required for the propylene//propylene/olefin block copolymer,a ratio ([η]_(A)/[η]_(B)) an intrinsic viscosity of segment A ([η]_(A))to an intrinsic viscosity of segment B ([η]_(B)) is controlled topreferably 0.5-2, more preferably 0.6-1.8 and most preferably 0.6-1.6.

The intrinsic viscosity of segment B ([η]_(B)) is obtained from theintrinsic viscosity of segment A ([η]_(A)) which can be measureddirectly, an intrinsic viscosity of the propylene//propylene/olefinblock copolymer ([η]_(W)) and a weight fraction of segment A (W_(A)) inthe propylene//propylene/olefin block copolymer, in accordance withfollowing equation:

[η]_(B)=([η]_(W)−W_(A)·[η]_(A))/(1−W_(A)).

The first process for the production of the presentpropylene//propylene/olefin block copolymer comprises carrying out insequence the following steps (A) and (B):

(A) a first polymerization step wherein propylene alone or a mixture ofpropylene and other olefin(s) than propylene is polymerized in thepresence of a catalyst system for olefin polymerization comprising asupported metallocene catalyst and an organoaluminum compound, toproduce the segment A comprising a polymer based on propylene, and

(B) a second polymerization step wherein propylene and other olefin(s)than propylene are copolymerized in the presence of the polymer based onpropylene containing the catalyst system for olefin polymerization fromthe first polymerization step, to produce the segment B comprising thepropylene/olefin random copolymer.

Another process of producing the propylene//propylene/olefin blockcopolymer comprises carrying out in sequence the same firstpolymerization step as in (A) above and the same second polymerizationstep as in (B) above, using the catalyst system for olefinpolymerization which comprises the preactivated catalyst comprising agranular product wherein 0.01-100 kg of the olefin prepolymer per kg ofthe supported metallocene catalyst is supported on the supportedmetallocene catalyst, and an organoaluminum compound, in place of thecatalyst system for olefin polymerization comprising the supportedmetallocene catalyst and the organoaluminum compound in the firstpolymerization step (A).

The term “preactivation” as used herein about the catalyst means thatvarious activities of the catalyst on the polymerization of olefin(s)including propylene, for example, a polymerization activity expressed bythe amount of olefin(s) polymerized per unit weight of an effectivecomponent of the catalyst and the activities acting on stereoregularityand crystallizability of the olefin polymer produced are preactivatedprior to the run polymerization of olefin. The term “repolymerization”of olefin means prepolymerizing small amounts of olefin in the presenceof the catalyst prior to the run polymerization of olefin for thepreactivation of the catalyst. The term “olefin prepolymer” means anolefin polymer which has been prepolymerized prior to the runpolymerization of olefin.

In the present invention, the supported metallocene catalyst comprises asolid product wherein a reaction product of an organic transition metalcompound having two π-electron conjugated ligands crosslinked eachother, what is called crosslinked metallocene compound (called hereafter“crosslinked metallocene compound”) and aluminoxane is supported on aninorganic finely particulate support, and also the solid product issolid particles containing 0.01-5% by weight of a transition metalderived from the crosslinked metallocene compound and 0.1-50% by weightof aluminum derived from aluminoxane and further having a molar ratio ofaluminum/transition metal in the supported metallocene catalyst in therange of 1-1,000.

The content of the transition matal in the supported metallocenecatalyst and the molar ratio of aluminum/transition metal act on thepolymerization activity of olefin(s). If the content of the transitionmetal is too little, no practical polymerization activity of olefin isobtained. If the content is more than is necessary, no polymerizationactivity according thereto is obtained. The content of the transitionmetal in the supported metallocene catalyst in the range of 0.01-5% byweight can provide practically sufficient olefin polymerizationactivity, but the range of 0.03-2% by weight is preferable. The contentof aluminum is 0.1-50% by weight, preferably 1-40% by weight. The molarratio of aluminum/transition metal is controlled to the range of1-1,000, preferably 5-700, and more preferably 10-500.

Further, the supported metallocene catalyst has a specific peak at 1426cm⁻¹ in the infrared (IR) absorption spectrum determined by an infraredreflection method, using an infrared absorption apparatus with aresolution of 4 cm⁻¹ equipped with a diffuse reflection accessory as aheating cell (Nicolet 60SXR, manufactured by Japan Optics Co., Ltd.) andfilling a sample in a diffuse reflection accessory in a N₂ sealed glowbox. The presence of this peak and the strength demonstrate the improvedpolymerization activity of olefin.

The supported metallocene catalyst as described above is prepared bycarrying out in sequence the following steps of:

(a) reacting the crosslinked metallocene compound with aluminoxane in aninert solvent,

(b) contacting a reaction product formed in step (a) with an inorganicfinely particulate support at a temperature of 85-150° C. in thepresence of an inert solvent, and

(c) washing at least two times a slurry containing the solid productformed in step (b) with an aliphatic hydrocarbon at a temperature of −50to 50° C.

The preactivated catalyst as described above is prepared by carryingout, subsequent to the above step (c), step (d) wherein the supportedmetallocene catalyst prepared in step (c) is contacted with olefin(s) toprepolymerize the olefin(s) and 0.01-100 kg of the olefin prepolymer perkg of the supported metallocene catalyst is further supported.

The metallocene compounds used for supported metallocene catalysts andpreactivated catalysts are represented by the following formula (1):

wherein M represents a transition metal, p represents a valence of atransition metal, X may be the same or different and each represents ahydrogen atom, a halogen atom or a hydrocarbyl radical, R¹ and R² may bethe same or difference and each represents a π-electron conjugatedligand coordinated to M, and Q represents a divalent radicalcrosslinking two π-electron conjugated ligands R¹ and R².

The transition metals represented by M in formula (1) include, forexample, Y, Sm, Zr, Ti, Hf, V, Nb, Ta and Cr. Preferable is Y, Sm, Zr,Ti or Hf, and particularly preferable is Zr or Hf.

The π-electron conjugated ligands represented by R¹ and R² in formula(1) include ligands which have a η-cyclopentadienyl structure, aT-benzene structure, a η-cycloheptatrienyl structure and aη-cyclooctatetraene structure. Particularly preferable is a ligandhaving a η-cyclopentadienyl structure.

The ligands having a η-cyclopentadienyl structure include, for example,a cyclopentadienyl group, an indenyl group, a hydrogenated indenyl groupand a fluorenyl group. These groups may be further substituted with ahydrocarbon group such as halogen, alkyl, aryl, aralkyl, alkoxy oraryloxy, a hydrocarbyl radical-containing silyl group such astrialkylsilyl, or a linear or cyclic alkylene group.

The groups represented by Q crosslinking R¹ and R² in formula (1)include any divalent radicals, but not limited thereto, for example, astraight or branched chain alkylene group, an unsubstitutedor.substituted cycloalkylene group, an alkylidene group, anunsubstituted or substituted cycloalkylidene group, an unsubstituted orsubstituted phenylene group, a silylene group, a dialkyl-substitutedsilylene group, a germyl group, a dialkyl-substituted germyl group andthe like.

The above crosslinked metallocene compounds include, for example,dimethylsilylene(3-t-butylcyclopentadienyl)(fluorenyl)zirconiumdichloride,dimethylsilylene(3-t-butylcyclopentadienyl)(fluorenyl)hafniumdichloride, rac-ethylenebis(indenyl)zirconium dimethyl,rac-ethylenebis(indenyl)zirconium dichloride,rac-dimethylsilylenebis(indenyl)zirconium dimethyl,rac-dimethylsilylenebis(indenyl)zirconium dichloride,rac-ethylenebis(tetrahydroindenyl)zirconium dimethyl,rac-dimethylgermylbis(indenyl)zirconium dimethyl,rac-dimethylgermylbis(indenyl)zirconium dichloride,rac-ethylenebis(tetrahydroindenyl)zirconium dimethyl,rac-ethylenebis(tetrahydroindenyl)zirconium dichloride,rac-dimethylsilylenebis(tetrahydroindenyl)zirconium dimethyl,rac-dimethylsilylenebis(tetrahydroindenyl)zirconium dichloride,rac-dimethylgermylbis(tetrahydroindenyl)zirconium dimethyl,rac-dimethylgermylbis(tetrahydroindenyl)zirconium dichloride,rac-dimethylsilylenebis(2-methyl-4,5,6,7-tetrahydroindenyl)zirconiumdichloride,rac-dimethylsilylenebis(2-methyl-4,5,6,7-tetrahydroindenyl)zirconiumdimethyl,rac-dimethylgermylbis(2-methyl-4,5,6,7-tetrahydroindenyl)zirconiumdichloride,rac-dimethylgermylbis(2-methyl-4,5,6,7-tetrahydroindenyl)zirconiumdimethyl, rac-ethylenebis(2-methyl-4,5,6,7-tetrahydroindenyl)hafniumdichloride, rac-dimethylsilylenebis(2-methyl-4-phenylindenyl)zirconiumdichloride, rac-dimethylsilylenebis(2-methyl-4-phenylindenyl)zirconiumdimethyl, rac-dimethylgermylbis(2-methyl-4-phenylindenyl)zirconiumdichloride, rac-dimethylgermylbis(2-methyl-4-phenylindenyl)zirconiumdimethyl, rac-dimethylsilylenebis(2-methyl-4-phenylindenyl)hafniumdichloride, rac-dimethylsilylenebis(2-methyl-4-naphthylindenyl)zirconiumdimethyl, rac-dimethylsilylenebis(2-methyl-4-naphthylindenyl)hafniumdichloride, rac-dimethylgermylbis(2-methyl-4-naphthylindenyl)zirconiumdimethyl, rac-dimethylgermylbis(2-methyl-4-naphthylindenyl)hafniumdichloride, rac-dimethylsilylenebis(2-methyl-4,5-benzindenyl)zirconiumdichloride, rac-dimethylsilylenebis(2-methyl-4,5-benzindenyl)zirconiumdimethyl, rac-dimethylgermylbis(2-methyl-4,5-benzindenyl)zirconiumdichloride, rac-dimethylgermylbis(2-methyl-4,5-benzindenyl)zirconiumdimethyl, rac-dimethylsilylenebis(2-methyl-4,5-benzindenyl)hafniumdichloride, rac-dimethylsilylenebis(2-ethyl-4-phenylindenyl)zirconiumdichloride, rac-dimethylsilylenebis(2-ethyl-4-phenylindenyl)zirconiumdimethyl, rac-dimethylgermylbis(2-ethyl-4-phenylindenyl)zirconiumdichloride, rac-dimethylsilylenebis(2-ethyl-4-phenylindenyl)hafniumdichloride,rac-dimethylsilylenebis(2-methyl-4,6-diisopropylindenyl)zirconiumdichloride,rac-dimethylsilylenebis(2-methyl-4,6-diisopropylindenyl)zirconiumdimethyl,rac-dimethylgermylbis(2-methyl-4,6-diisopropylindenyl)zirconiumdichloride,rac-dimethylsilylenebis(2-methyl-4,6-diisopropylindenyl)hafniumdichloride,dimethylsilylene(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)titaniumdichloride,dimethylsilylene(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)zirconiumdichloride,dimethylsilylene(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)zirconiumdimethyl,dimethylgermyl(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)zirconiumdichloride,dimethylgermyl(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)zirconiumdimethyl,dimethylsilylene(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)hafniumdichloride,dimethylsilylene(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)hafniumdimethyl,dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)titaniumdichloride,dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)zirconiumdichloride,dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)zirconiumdimethyl,dimethylgermyl(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)zirconiumdichloride,dimethylgermyl(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)zirconiumdimethyl,dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)hafniumdichloride, anddimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)hafniumdimethyl.

Of the above-mentioned crosslinked metallocene compounds, particularlypreferable aredimethylsilylene(3-t-butylcyclopentadienyl)(fluorenyl)zirconiumdichloride, rac-dimethylsilylenebis(2-methyl-4-phenylindenyl)zirconiumdichloride, rac-dimethylgermylbis(2-methyl-4-phenylindenyl)zirconiumdichloride, rac-dimethylgermylbis(2-methyl-4-phenylindenyl)zirconiumdichloride, rac-dimethylsilylenebis(2-methyl-4-naphthylindenyl)zirconium dichloride,rac-dimethylgermylbis(2-methyl-4-naphthylindenyl)zirconium dichloride,rac-dimethylsilylenebis(2-methyl-4,5-benzindenyl)zirconium dichloride,rac-dimethylgermylbis(2-methyl-4,5-benzindenyl)zirconium dichloride,rac-dimethylsilylenebis(2-ethyl-4-phenylindenyl)zirconium dichloride,rac-dimethylgermylbis(2-ethyl-4-phenylindenyl)zirconium dichloride,rac-dimethylsilylenebis(2-methyl-4,6-diisopropylindenyl)zirconiumdichloride,rac-dimethylgermylbis(2-methyl-4,6-diisopropylindenyl)zirconiumdichloride,dimethylsilylene(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)zirconiumdichloride,dimethylsilylene(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)zirconiumdimethyl,dimethylgermyl(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)zirconiumdichloride,dimethylgermyl(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)zirconiumdimethyl,dimethylsilylene(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)hafniumdichloride,dimethylsilylene(2,4-dimethylcyclopentadienyl)(3′,5′-dimethylcyclopentadienyl)hafniumdimethyl,dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′,-trimethylcyclopentadienyl)zirconium dichloride,dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)zirconium dimethyl, dimethylgermyl (2,3, 5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)zirconium dichloride, dimethylgermyl(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)zirconiumdimethyl,dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)hafniumdichloride, anddimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)hafniumdimethyl.

Most preferable crosslinked metallocene compounds aredimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)zirconiumdichloride,dimethylgermyl(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)zirconiumdichloride,dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)hafniumdichloride and rac-dimethylsilylene(2-methyl-4-phenylindenyl)zirconiumdichloride.

The crosslinked metallocene compounds may contain their meso compoundscorresponding to the above-recited racemic compounds, if they are assmall as 5 mol % or less.

Aluminoxanes which are reacted with the above crosslinked metallocenecompounds in step (a) above are represented by the following formula (2)or (3).

wherein R³ is a hydrocarbyl radical of 1 to 6 carbons, preferably 1 to 4carbons, e.g., an alkyl group such as methyl, ethyl, propyl, butyl,isobutyl, pentyl, hexyl, etc.; an alkenyl group such as allyl,2-methylallyl, propenyl, isopropenyl, 2-methyl-1-propenyl, butenyl,etc.; a cycloalkyl group such as cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, etc.; and an aryl group, etc.; and each R³ may be the sameor different. Of these groups, an alkyl group is preferable and methylis most preferable. q is an integer of 4 to 30, preferably 6 to 30, andmost preferably 8 to 30.

As aluminoxanes, a solution of aluminoxane in a commercially availableorganic solvent can be used. Further, aluminoxanes can be prepared underknown various conditions. The following methods for the preparation ofaluminoxanes can be concretely illustrated:

A method of reacting a trialkyl aluminum, e.g., trimethyl aluminum,triisobutyl aluminum or the mixture thereof, directly with water in anorganic solvent such as toluene, ether, etc.;

A method of reacting a trialkyl aluminum, e.g., trimethyl aluminum,triisobutyl aluminum or the mixture thereof, with salts containingcrystal water, e.g., copper sulfate hydrate and aluminum sulfatehydrate; and

A method of reacting water impregnated in silica gel or the like, with atrialkyl aluminum, e.g., trimethyl aluminum, triisobutyl aluminum,separately or simultaneously or successively.

Even if unreacted trialkyl aluminum remains in the aluminoxane preparedby these methods, there is no trouble especially.

In step (a), 10-1,000 mols, preferably 20-500 mols (in terms of analuminum atom) of aluminoxane per mol of the crosslinked metallocenecompound are reacted in an inert solvent at a temperature of −50 to 100°C., preferably 0 to 50° C. for one minute to 10 hrs, preferably 3minutes to 5 hrs to prepare a reaction product of the crosslinkedmetallocene compound and aluminoxane.

The use of inert solvents is preferable in proceeding the reactionuniformly and efficiently. There is no restriction especially in theamount of the inert solvent used, but usually about 10-10,000 liters,preferably about 10-1,000 liters are used per mol of the metallocenecompound.

The inert solvents used in the above reaction include, for example,aromatic hydrocarbons such as benzene, toluene, xylene, cumene, etc.;aliphatic hydrocarbons such as butane, tetramethylbutane, pentane,ethylpentane, trimethylpentane, hexane, methylhexane, ethylhexane,dimethylhexane, heptane, methylheptane, octane, nonane, decane,hexadecane, octadecane, etc.; alicyclic hydrocarbons such ascyclopentane, methylcyclopentane, cyclohexane, cyclooctane, etc.;halogenated hydrocarbons wherein said aromatic hydrocarbons, saidaliphatic hydrocarbons or said alicyclic hydrocarbons are substituted byhalogen; and the mixtures thereof. Ethers such as ethylether,tetrahydrofuran, etc. can also be used. Preferable inert solvents arearomatic hydrocarbons. Further, commercially available solvents foraluminoxane solution may be used in the reaction as such or incombination with other aromatic hydrocarbons or the like.

In step (b) which follows step (a), the reaction product of thecrosslinked metallocene compound and aluminoxane prepared in step (a) iscontacted with an inorganic finely particulate support at a temperatureof 85-150° C. in the presence of the inert solvent used as a reactionsolvent in step (a) to produce a solid product wherein the reactionproduct is supported on the inorganic finely particulate support. Inthis contact reaction, an additional inert solvent may be added as theneed arises.

A ratio of the reaction product of the crosslinked metallocene compoundand aluminoxane prepared in step (a) to the inorganic finely particulatesupport is 1 to 1,000 kg, preferably 5 to 500 kg of the inorganic finelyparticulate support per mol of the transition metal atom in the reactionproduct. The amount of inert solvent used is 10-10,000 liters,preferably 10-1,000 liters per mol of the transition metal atom in thereaction product.

The inorganic finely particulate supports contacted with the reactionproduct are inorganic compounds or the mixtures thereof and aregranulated or spherical, solid fine particles having a particle size of5-300 μm, preferably 10-200 μm. The specific surface of inorganic finelyparticulate supports is in the range of 50-1,000 m²/g, preferably100-700 m²/g, and the pore volume is preferably in the range of 0.3-2.5m³/g.

Preferred inorganic finely particulate supports. are metal oxides, e.g.,SiO₂, Al₂O₃, MgO, TiO₂, ZrO, etc., and the mixture thereof or thecomposite oxides thereof. The supports comprising SiO₂ or Al₂O₃ as amain component are especially preferable. More specific inorganiccompounds include SiO₂, Al₂O₃, MgO, SiO₂—Al₂O₃, SiO₂—MgO, SiO₂—TiO₂,SiO₂—Al₂O₃—MgO, etc. SiO₂ is especially preferable.

These inorganic finely particulate supports are used after fired usuallyat a temperature of 100-1,000° C., preferably 300-900° C., mostpreferably 400-900° C. The amount adsorbed on the surface of the firedinorganic finely particulate support is not more than 0.1% by weight,preferably not more than 0.01% by weight. The content of hydroxyl groupon the surface of the support is not less than 1.0% by weight,preferably 1.5-4.0% by weight, and more preferably 2.0-3.5% by weight.These inorganic finely particulate supports may be subjected to acontact treatment with an organoaluminum compound and/or ahalogen-containing silicone compound, prior to the use.

The contact of the reaction product prepared in step (a) with theinorganic finely particulate support is performed at a temperature of85-150° C., preferably 90-130° C., most preferably 95-120° C. for 5minutes to 100 hrs, preferably 10 minutes to 50 hrs. In particular, thetemperature condition is an important factor. The contact within theabove temperature range can achieve high polymerization activity of theresultant catalyst for olefin polymerization, and high bulk density andgood particle morphology of the propylene//propylene/olefin blockcopolymer produced using said catalyst in the polymerization of thepropylene//propylene/olefin.

In the subsequent step (c), the solid product containing the inertsolvent prepared in step (b) is washed at least two times with analiphatic hydrocarbon at a temperature of −50 to 50° C. to prepare thesupported metallocene catalyst comprising the solid product having thereaction product of the crosslinked metallocene compound and aluminoxanesupported on the support.

The aliphatic hydrocarbons used for washing include aliphatichydrocarbons recited above as inert solvents and these mixed solvents.Preferably, n-hexane, isopentane or the mixture thereof is used.

The methods for washing the solid product prepared in step (b) which canbe employed in the invention include, for example, a method whereinafter completion of step (b), an inert solvent is separated from aslurry comprising the inert solvent and the solid product, byfiltration, centrifugal separation or decantation, etc. and theresultant solid product is washed with an aliphatic hydrocarbon, and amethod wherein after completion of step (b), without separating an inertsolvent from a slurry comprising the inert solvent and the solidproduct, an aliphatic hydrocarbon is added to separate a mixed solventof the inert solvent and the aliphatic hydrocarbon in the same manner asdescribed above and the resultant solid product is washed with analiphatic hydrocarbon, or the like. The latter method is morepreferable.

The washing of the solid product is repeated using 1-500 liters,preferably 10-100 liters of the aliphatic hydrocarbon per kg of theinorganic finely particulate support per washing, under the temperaturecondition of −50 to 50° C., preferably −30 to 40° C, most preferably −30to 30° C., until no metallocene compound is dissolved out in thealiphatic hydrocarbon after washing. Washing at least two times, usuallynot less than four times is sufficient, but not limited thereto.

The temperature condition for washing is an important factor. Washingwithin the above temperature range can achieve high polymerizationactivity of the resultant catalyst for olefin polymerization, and highbulk specific gravity and good particle morphology of thepropylene//propylene/olefin block copolymer produced using said catalystin the polymerization of the propylene//propylene/olefin.

The supported metallocene catalysts prepared by the above-mentionedmethods are used suitably for the manufacture of the presentpropylene//propylene/olefin block copolymer, in combination with theorganoaluminum compounds. Further, they can be used as a catalyst systemfor usual olefin polymerization carried out by a gas phasepolymerization process or a bulk polymerization process.

A granular preactivated catalyst wherein an olefin prepolymer is coatedand supported on the solid product prepared in step (c) can be preparedby carrying out, subsequently to the above step (c), further step (d)wherein the supported metallocene catalyst prepared in step (c) iscontacted with an olefin to prepolymerize the olefin and 0.01-100 kg ofthe olefin prepolymer per kg of the supported metallocene catalyst arefurther supported.

Olefin prepolymers supported on the preactivated catalyst includehomopolymers and copolymers of olefin(s) of 2-20 carbons, e.g.,ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene,2-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene or thelike. In particular, ethylene homopolymer, propylene homopolymer, andolefin copolymers based on ethylene or propylene are suitable. Further,these olefin prepolymers preferably have an intrinsic viscosity [η] of0.1-10 dl/g, preferably 0.2-7 dl/g, as determined in decalin at 135° C.

A preferable process for the prepolymerization of olefin(s) is a processof introducing an olefin into a slurry of the solid product obtained instep (c), i.e., the supported metallocene catalyst dispersed in analiphatic hydrocarbon, to prepolymerize the olefin. As the slurry of thesolid product dispersed in the aliphatic hydrocarbon, a solid productobtained by washing at the final stage of step (c) may be used as suchwithout separation from the aliphatic hydrocarbon, or a separated solidproduct may be used after redispersing in the same aliphatichydrocarbon.

Prepolymerization of an olefin can be conducted in liquid phase usingthe olefin itself to be polymerized as a solvent or in gas phase withoutany solvent, but it is preferably carried out in the presence of analiphatic hydrocarbon to control the polymerization of a small quantityof olefin and promote a homogenous reaction.

The prepolymerization of olefin in the aliphatic hydrocarbon isconducted by introducing 0.01 to 1,000 kg, preferably 0.1 to 500 kg ofan olefin into a slurry comprising 0.005 to 5 m³, preferably 0.01 to 1m³ of an aliphatic hydrocarbon per kg of the solid product, followed bypolymerization of the olefin at a temperature of −50 to 100° C,preferably 0 to 50° C., for one minute to 50 hrs, preferably 3 minutesto 20 hrs.

In the prepolymerization of olefin as described above, there is no needto add a cocatalyst, a typical example of which is an organoaluminumcompound such as trialkylaluminum and aluminoxane, since a reactionproduct of the crosslinked metallocene compound and aluminoxane has beensupported on the solid product. The cocatalyst may be added, if desired.The amount of the cocatalyst added is preferably within the range of notmore than 1,000 mols, preferably not more than 500 mols (in terms of analuminum atom) per mol of a transition metal atom in the solid product.Further, the prepolymerization of olefin may be carried out in thepresence of hydrogen to control the molecular weight of the resultingolefin prepolymer.

The preactivated catalysts as prepared above are used suitably for themanufacture of the present propylene//propylene/olefin block copolymers,as a catalyst system for olefin polymerization in combination with theorganoaluminum compound, in the slurry state after completion of theprepolymerization of olefin, or in the resuspended state in an aliphatichydrocarbon after completion of the prepolymerization of olefin andwashing with the aliphatic hydrocarbon, or in the dry state byseparation of the aliphatic hydrocarbon. Further, the catalyst systemfor olefin polymerization can be used in conventional olefinpolymerization according to a slurry polymerization process, a gas phasepolymerization process and a bulk polymerization process.

In the first polymerization step (A) of the present invention, propyleneor a mixture of propylene and other olefins than propylene ispolymerized in the presence of a catalyst system for olefinpolymerization comprising a combination of the above supportedmetallocene catalyst and the organoaluminum compound or a combination ofthe above preactivated catalyst and the organoaluminum compound, toproduce 20-95% by weight of segment A comprising the polymer based onpropylene, based on the total weight of the polymer.

The organoaluminum compound constituting the catalyst system for olefinpolymerization is a compound represented by the formula: AlR⁴ _(s)R⁵_(t)X_(3−(s+t)) wherein R⁴ and R⁵ are each independently a hydrocarbylradical such as an alkyl group of 1-10 carbons, a cycloalkyl group, anaryl group or the like, a phenyl group which may have substituent(s)such as an alkoxy group, a fluorine atom, methyl, trifluorophenyl or thelike, X is a halogen atom, and s and t are any integer satisfying0<s+t≦3.

The organoaluminum compounds represented by the above formula include,e.g., a trialkylaluminum such as trimethylaluminum, triethylaluminum,tri-isopropylaluminum, tri-iso-butylaluminum, tri-n-butylaluminum,tri-n-hexylaluminum, tri-n-octylaluminum or the like; a dialkylaluminumhalide such as dimethylaluminum chloride, dimethylaluminum bromide,diethylaluminum chloride, diisopropylaluminum chloride or the like; analkylaluminum sesquihalide such as methylaluminum sesquichloride,ethylaluminum sesquichloride, ethylaluminum sesquibromide,isopropylaluminum sesquichloride or the like; and the mixtures of thesetwo or more compounds. Preferable is a trialkylaluminum.

The amount of the organoaluminum compound used ranges from 1 to 5,000mols (in terms of an Al atom in the organoaluminum compound), preferably5 to 3,000 mols and most preferably 10 to 1,000 mols per mol of thetransition metal atom in the catalyst system.

The amount of the supported metallocene catalyst or the preactivatedcatalyst used ranges is from 1×10⁻¹⁰ to 1×10⁻³ mol, preferably 1×10⁻⁹ to1×10⁻⁴ mol in terms of the transition metal atom in the catalyst system,per liter of a polymerization volume. The amount of the catalyst used inthe above range can keep an efficient and controlled reaction rate of apolymerization of olefin.

The term “polymerization volume” as used herein means a volume of aliquid phase section within a polymerization reactor in case of a liquidphase polymerization, and a volume of a gas phase section within apolymerization reactor in case of a gas phase polymerization.

In the second polymerization step (B) which follows the firstpolymerization step (A), a mixture of propylene and other olefin(s) thanpropylene is copolymerized in the presence of the polymer based onpropylene containing the catalyst system for olefin polymerization toproduce 80-95% by weight of segment B comprising the propylene/olefinrandom copolymer, based on the total weight of the polymer, thusproducing the aimed propylene//propylene/olefin block copolymer.

A process for the polymerization of propylene and propylene/olefinemployed in the first polymerization step and the second polymerizationstep can be known olefin polymerization processes. They include, forexample, a slurry polymerization process wherein an olefin ispolymerized in an inert solvent including an aliphatic hydrocarbon suchas butane, pentane, hexane, heptane, isooctane or the like, an alicyclichydrocarbon such as cyclopentane, cyclohexane, methylcyclohexane or thelike, an aromatic hydrocarbon such as toluene, xylene, ethylbenzene orthe like, and gasoline fraction, hydrogenated diesel oil and the like; abulk polymerization process wherein an olefin itself such as propyleneis used as a solvent; a gas phase polymerization process wherein anolefin is polymerized in gas phase; and a combination of these two ormore polymerization processes. The catalysts used in the process for theproduction of the present invention can be employed suitably when thesecond polymerization step is performed by a gas phase polymerization,in particular, when both the first polymerization step and the secondpolymerization step are performed by a gas phase polymerization. Thisprocedure can provide more efficient processes for the production of thecopolymer with good performance and can produce excellent copolymerswith well-balanced particle morphology and physical property.

The polymerization conditions for segment A comprising the polymer basedon propylene in the first polymerization step (A) include thepolymerization temperature of 20-120° C., preferably 40-100° C. and thepolymerization pressure of atmospheric pressure to 9.9 MPa, preferably0.59 to 5.0 MPa, in the presence of the above-described catalyst systemfor olefin polymerization. If necessary, a molecular weight modifiersuch as hydrogen may be used to control an intrinsic viscosity [η]_(A)of segment A to a desired value.

The copolymerization conditions for segment B comprising thepropylene/olefin random copolymer in the second polymerization step (B)include the polymerization temperature of 20-120° C., preferably 40-100°C. and the polymerization pressure of atmospheric pressure to 9.9 MPa,preferably 0.59 to 5.0 MPa. Similarly to the first polymerization step,if necessary, a molecular weight modifier such as hydrogen may be usedto control an intrinsic viscosity [η]_(B) of segment B to a desiredvalue.

A polymerization ratio of segment A comprising the polymer based onpropylene to segment B comprising the propylene/olefin/random copolymeris controlled by known processes which include the regulation of thepolymerization time, polymerization pressure and polymerizationtemperature, respectively in the first polymerization step and thesecond polymerization step and the use of the regulator for thepolymerization activity of the catalyst such as carbon monoxide andhydrogen sulfide upon copolymerization in the second polymerizationstep.

In the present invention, the first polymerization step (A) and thesecond polymerization step (B) may be carried out using one or morepolymerization vessels for each step. Any of batch-wise, semi-continuousand continuous methods may be employed.

After completion of the copolymerization in the second polymerizationstep (B), unreacted monomer and hydrogen are separated from thepolymerization system in case of the gas phase polymerization, or thesolvent is separated after deactivation of the catalyst in case of thebulk polymerization and the slurry polymerization, thereby producing agranular propylene//propylene/olefin block copolymer.

The propylene//propylene/olefin block copolymer produced by theprocesses of the present invention may be incorporated, if necessary,with various additives such as antioxidants, ultraviolet absorbingagents, antistatic agents, nucleating agents, lubricants, flameretardants, antiblocking agents, colorants, inorganic or organicfillers, and further, various synthetic resins. Thereafter, the blockcopolymer is usually melt-kneaded at a temperature of 190-350° C. forabout 20 seconds to 30 minutes using a melt-kneading machine and, ifnecessary, extruded into strands, and further cut into granulates, i.e.,pellets which are served as a molding material.

The present invention is further illustrated by the following Examplesand Comparative Examples.

Evaluation Items:

In the following Examples and Comparative Examples, the followingvarious properties were evaluated.

(1) ZY: Olefin polymerization activity wherein the amount (g) of thepolymerized olefin per gram of the transition metal Zr atom in thecrosslinked metallocene compound was calculated from the amount of thesupported metallocene catalyst used or the preactivated catalyst usedand the amount of the produced polymer (Unit: g·polymer/g·Zr).

(2) BD: Bulk density of the produced polymer (Unit: kg/m³).

(3) [η]: Intrinsic viscosity determined at 135° C. with tetralin(tetrachloronaphthalene) as a solvent using an automatic viscositymeasuring apparatus (AVS2 type, manufactured by Mitsui Toatu K.K.)(Unit: dl/g).

(4) MFR: Value measured under condition 14 of Table 1 (load 21.18N, 230°C.) in accordance with JIS K7210 (Unit: g/10 min).

(5) Flexural modulus (MPa): Evaluated by flexural test. The resultantpellets were formed by an injection-molding method into a specimen 100mm in length, 10 mm in width and 4 mm in thickness. The specimen wasdetermined for the flexural modulus in accordance with JIS K7203.

(6) Izod impact strength (kJ/m²): Value determined at 0° C. inaccordance with JIS K7110 using a notched specimen prepared by aninjection-molding method under the same condition as that of theflexural modulus.

(7) Haze (%): Measured in accordance with the method described in JISK7105, using a specimen 1 mm in thickness. The specimen was prepared inthe same manner as described for the measurement of flexural modulus.

EXAMPLE 1

(1) Preparation of Supported Metallocene Catalyst

A 4-L glass reaction vessel equipped with a stirrer and purged withnitrogen was charged with 1.37 liter (4.11 mol in terms of Al atom) of atoluene solution of methylaluminoxane (concentration: 3 mol/L, tradename: PMAO manufactured by Tosoh Akzo K.K.), and 16.6 mmol of a mixtureof chiraldimethylsilylene(2,3,5-trimethy1cyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)zirconiumdichloride and its meso form,dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,3′,5′-trimethylcyclopentadienyl)zirconiumdichloride (1 mol % of meso content) as a crosslinked metallocenecompound, and the mixture was reacted at 25° C. for 30 minutes whilestirring to obtain a reaction product of the metallocene compound andaluminoxane.

To the reaction vessel was added 100 g of silica having an averageparticle size of 51 μm (SYLOPOL® 948, manufactured by Grace Davison)which had been fired at 750° C. under reduced pressure for 8 hrs, andthe temperature of the vessel was elevated to 100° C. Then, the reactionproduct obtained above and the silica were contacted while stirring for1 hour to give a slurry containing a solid product on which the abovereaction product was supported.

After the reaction vessel was cooled to −10° C., 2 liters of n-hexanewere added and the mixture was stirred for 5 minutes. The stirrer wasstopped and the solvent was separated by decantation.

Subsequently, 2 liters of n-hexane were added to the vessel, whilekeeping the temperature of the vessel at −10° C. The mixture was stirredand washed for 5 minutes, the stirrer was stopped, and the washingsolvent was separated by decantation. This washing operation wasrepeated four times to obtain a solid product on which the reactionproduct of the metallocene compound and aluminoxane was supported, i.e.,a supported metallocene catalyst. Additional 2 liters of n-hexane werecharged in the vessel and the supported metallocene catalyst wasdispersed to form a slurry.

A part of the resulting supported metallocene catalyst/n-hexane slurrywas taken, and the solvent was separated from the slurry, which was thendried under reduced pressure to give the supported metallocene catalyst.Analysis of the resultant catalyst showed that it contained 0.61% byweight of Zr derived from the crosslinked metallocene compound and 18.2%by weight of Al derived from aluminoxane and also that it had aspeicific peak at 1426 cm⁻¹ in the IR spectrum, from which it wasconfirmed that the reaction product of the crosslinked metallocenecompound and methylaluminoxane was supported on the silica.

The IR spectrum of the resulting supported metallocene catalyst is shownin FIG. 1.

No agglomerate with a particle size of 350 μm or more was observed inthe resulting supported metallocene catalyst.

(2) Production of Preactivated Catalyst

A 4-dm³ stainless reaction vessel equipped with a stirrer and purgedwith nitrogen was charged with 2 liters of n-hexane. The supportedmetallocene catalyst/n-hexane slurry prepared in (1) was transferred tothe vessel kept at 0° C. While keeping the vessel at 0° C. withstirring, propylene gas was fed for 90 minutes at a rate of 0.15 mol/minto carry out the prepolymerization. The resulting propylene homopolymerwas supported on the supported metallocene catalyst prepared in (1).During this prepolymerization reaction, unreacted propylene gas wasdischarged out of the vessel. After the prepolymerization time passed,the supply of propylene gas was stopped. While elevating the temperatureof the vessel to 25° C., a gas phase in the reaction vessel was purgedwith nitrogen.

After the solvent was separated from the reaction mixture bydecantation, 2 liters of n-hexane were added, the preactivated catalystwas stirred and washed for 5 minutes, and the washing solvent wasseparated by decantation. This washing operation was repeated fourtimes. Additional 2 liters of n-hexane were added to the vessel and theresulting preactivated catalyst was dispersed in n-hexane to form aslurry.

A part of the resulting preactivated catalyst/n-hexane slurry was taken,and the solvent was separated from the slurry, which was then driedunder reduced pressure to give a preactivated catalyst. Analysis of theresultant preactivated catalyst showed that 0.7 g of polypropylene per 1g of the supported metallocene catalyst was supported.

(3) Production of Propylene//propylene/olefin Block Copolymer

A 3-L stainless gas phase polymerization reactor of a horizontal form(length/diameter=3), equipped with a stirrer and purged with nitrogen,was charged with 100 g of polypropylene powders. To the reactor wasintroduced with stirring 33 mg of the preactivated catalyst prepared in(2) and 0.2 mmol of triethyl aluminum (an n-hexane solution at aconcentration of 1 mol/L). The temperature of the reactor was elevatedto 50° C., and propylene was fed so as to maintain a pressure of thereactor at 1.87 MPa to continue a gas phase polymerization of propylenefor 2 hours. After the polymerization time passed, the supply of apropylene gas was stopped. An unreacted propylene was discharged out ofthe system and the temperature of the reactor was lowered to 25° C. Thepolymer was taken from the reactor while leaving about 100 g ofpolypropylene particles therein. Subsequently, the preactivated catalystwas introduced in the same amount as in the first polymerization step,and the same operation as in the first polymerization step was repeatedas the second propylene polymerization. The third propylenehomopolymerization repeating once more the same operation as describedabove was completed to produce the segment A comprising a propylenehomopolymer.

While leaving the resulting polymer in the polymerization reactor, thetemperature of the reactor was elevated to 50° C. and anethylene/propylene mixed gas (molar ratio=ethylene/propylene=94/6) wasfed to the reactor so as to maintain the pressure at 1.6 MPa. A gasphase copolymerization of ethylene/propylene was continued for 1 hour.After the polymerization time passed, the supply of theethylene/propylene mixed gas was stopped. Unreacted ethylene andpropylene were then discharged out of the system and the temperature ofthe reactor was lowered to 25° C. From the polymerization reactor, 420 gof the resultant propylene//propylene/ethylene block copolymer wererecovered.

After completion of the polymerization, neither generation of thepolymer in lump within the opened reactor, i.e., reactor chunking, noradhesion of the polymer on the wall surface of the reactor, i.e.,reactor fouling was observed.

The resultant propylene//propylene/ethylene block copolymer had anethylene content of 11.2% by weight, a Zr content of 0.66 ppm, anintrinsic viscosity [η]_(W) of 1.44 dl/g, a melting point of 155° C. andBD (bulk density) of 360 kg/m³.

Separately, the operation until the above first polymerization step wascarried out under the same condition to produce 340 g of polypropylenehaving an intrinsic viscosity [η]_(A) of 1.45 dl/g.

From the above result, it was calculated that segment A was 81% byweight, segment B was 19% by weight, an intrinsic viscosity [η]_(B) ofsegment B was 1.40 dl/g and an ethylene content in segment B was 58.9%by weight. Further, the polymerization activity, ZY was calculated to be1.5×10⁶ g polymer/g Zr.

EXAMPLE 2

(1) Preparation of Supported Metallocene Catalyst

A slurry of the supported metallocene catalyst dispersed in isopentanewas prepared in the same manner as in the preparation of the supportedmetallocene catalyst of Example 1(1), except that a reaction product ofthe metallocene compound and aluminoxane was contacted with silica at atemperature of 115° C. and that a solid product was washed at −5° C.with isopentane. Subsequently, separation of the solvent by filtrationand drying under reduced pressure at a temperature of 30° C. gave asupported metallocene catalyst comprising solid particles.

Analysis of the resultant supported metallocene catalyst showed that itcontained 0.58% by weight of Zr derived from the crosslinked metallocenecompound and 17.0% by weight of Al derived from aluminoxane.

No formation of an agglomerated catalyst with a particle size of 350 μmor more was observed.

(2) Production of Propylene//propylene/olefin Block Copolymer

A 3-L stainless polymerization reactor equipped with a stirrer andpurged with nitrogen was charged with 0.5 mmol of triethyl aluminum (ann-hexane solution at a concentration of 1 mol/L) and 1 liter of aliquefied propylene. After the temperature of the reactor was raised to50° C., ethylene was introduced into the reactor so as to provide apartial pressure of 0.1 MPa. 23 mg of the supported metallocene catalystprepared in (1) slurried in 2 ml of n-hexane were pressurized in thereactor together with 0.2 liter of a liquefied propylene and thepolymerization was initiated. After initiation of the polymerization,the temperature of the reactor was kept at 50° C. and the bulkcopolymerization of ethylene/propylene was continued for 2 hours. Afterthe polymerization time passed, unreacted ethylene and propylene weredischarged out of the system and the temperature of the reactor wascooled to 25° C.

While leaving the polymer based on propylene in the reactor, thetemperature of the reactor was elevated to 50° C., a mixed gas ofethylene/propylene (molar ratio of ethylene/propylene=92/8) was fed tothe reactor so as to keep the pressure of the reactor at 1.6 MPa and thegas phase copolymerization of ethylene/propylene was continued for onehour. After the polymerization time passed, the supply of anethylene/propylene mixed gas was stopped.

Unreacted ethylene and propylene were discharged out of the system, thetemperature of the reactor was lowered to 25° C. and 350 g of apropylene//propylene/ethylene block copolymer were recovered. Aftercompletion of the polymerization, neither generation of the polymer inlump within the opened reactor, i.e., reactor chunking, nor adhesion ofthe polymer on the wall surface of the reactor, i.e., reactor foulingwas observed.

The resultant propylene//propylene/ethylene block copolymer had anethylene content of 8.9% by weight, a Zr content of 0.38 ppm, anintrinsic viscosity [η]_(W) of 1.39 dl/g, a melting point of 153° C. andBD (bulk density) of 370 kg/m³.

Separately, the operation until the above first polymerization step wascarried out under the same condition to produce 340 g of anethylene/propylene copolymer based on propylene with an ethylene contentof 0.2% by weight and an intrinsic viscosity [η]_(A) of 1.41 dl/g.

From the above result, it was calculated that segment A was 86% byweight, segment B was 14% by weight, an intrinsic viscosity [η]_(B) ofsegment B was 1.27 dl/g and an ethylene content in segment B was 62.3%by weight. The polymerization activity, ZY was calculated to be 2.6×10⁶g polymer/g Zr.

Comparative Example 1

A propylene//propylene/ethylene block copolymer was produced in the samemanner as in Example 1, except that the supported metallocene catalystused was prepared by changing the temperature upon contact of thereaction product with silica to 60° C. from 100° C. in the preparationof the supported metallocene catalyst in Example 1(1).

The preparation conditions and results for the supported metallocenecatalyst and the preactivated catalyst are shown in Table 1. Thepreparation conditions and results for the propylene//propylene/ethyleneblock copolymer are shown in Table 2.

Comparative Example 2

A propylene//propylene/ethylene block copolymer was produced in the samemanner as in Example 1, except that toluene was substituted for n-hexaneas a solvent for washing the solid product in the preparation of thesupported metallocene catalyst in Example 1(1) and that the amount of apreactivated catalyst used was 190 mg in terms of the supportedmetallocene catalyst in the production of thepropylene//propylene/olefin block copolymer in Example 1(3), thepreactivated catalyst being prepared by preactivating the supportedmetallocene catalyst as prepared above under the same condition as inExample 1(2).

The preparation conditions and results for the supported metallocenecatalyst and the preactivated catalyst are shown in Table 1. Thepreparation conditions and results for the propylene//propylene/ethyleneblock copolymer are shown in Table 2.

EXAMPLE 3

(1) Preparation of Supported Metallocene Catalyst

A 2-L glass reaction vessel equipped with a stirrer and purged withnitrogen was charged with 0.58 liter (1.74 mol in terms of Al atom) of atoluene solution of methylaluminoxane (concentration: 3 mol/L, tradename: PMAO manufactured by Tosoh Akzo K.K.), and 6.96 mmol of a mixtureof chiraldimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,4′,5′-trimethylcyclopentadienyl)zirconiumdichloride and its meso form,dimethylsilylene(2,3,5-trimethylcyclopentadienyl)(2′,3′,5′-trimethylcyclopentadienyl)zirconiumdichloride (1 mol % of meso content) as a crosslinked metallocenecompound, and the mixture was reacted at 50° C. for 60 minutes whilestirring to obtain a reaction product of the metallocene compound andaluminoxane.

To the reaction vessel was added 50 g of silica having an averageparticle size of 51 μm (SYLOPOL® 948, manufactured by Grace Davison)which had been fired at 750° C. under reduced pressure for 8 hrs, andthe temperature of the vessel was elevated to 110° C. Then, the reactionproduct obtained above and the silica were contacted while stirring for1 hour to give a slurry containing a solid product on which the abovereaction product was supported.

After the reaction vessel was cooled to −20° C., 1 liter of n-hexane wasadded and the mixture was stirred for 10 minutes. The stirrer wasstopped and the solvent was separated by decantation.

Subsequently, 1 liter of n-hexane was added to the vessel, while keepingthe temperature of the vessel at −20° C. The mixture was stirred andwashed for 5 minutes, the stirrer was stopped, and the washing solventwas separated by decantation. This washing operation was repeated fourtimes to obtain a solid product on which the reaction product of themetallocene compound and aluminoxane was supported, i.e., a supportedmetallocene catalyst. Additional 1 liter of n-hexane was charged in thevessel and the supported metallocene catalyst was dispersed to form aslurry.

A part of the resulting supported metallocene catalyst/n-hexane slurrywas taken, and the solvent was separated from the slurry, which was thendried under reduced pressure to give the supported metallocene catalyst.Analysis of the resultant catalyst showed that it contained 0.46 % byweight of Zr derived from the crosslinked metallocene compound and 14.9%by weight of Al derived from methylaluminoxane.

No formation of an agglomerated catalyst with a particle size of 350 μmor more was observed.

(2) Production of Preactivated Catalyst

To a 2-L glass reaction vessel equipped with a stirrer and purged withnitrogen was transferred the supported metallocene catalyst/n-hexaneslurry prepared in (1) and the temperature of the reaction vessel wascontrolled to 0° C. While keeping the vessel at 0° C. with stirring,propylene gas was fed for 80 minutes at a rate of 53.2 mmol/min to carryout a prepolymerization. The resulting propylene homopolymer wassupported on the supported metallocene catalyst prepared above. Duringthis prepolymerization reaction, unreacted propylene gas was dischargedout of the vessel. After the prepolymerization time passed, the supplyof propylene gas was stopped. While elevating the temperature of thevessel to 25° C., a gas phase in the reaction vessel was purged withnitrogen.

After the solvent was separated from the reaction mixture bydecantation, 1 liter of n-hexane was added, the preactivated catalystwas stirred and washed for 5 minutes, and the washing solvent wasseparated by decantation. This washing operation was repeated fivetimes. Additional 1 liter of n-hexane was added to the vessel and theresulting preactivated catalyst was dispersed in n-hexane to form aslurry.

The resulting preactivated catalyst/n-hexane slurry was separated byfiltration and dried at 25° C. under reduced pressure to give apreactivated catalyst of solid particles.

Analysis of the resultant preactivated catalyst showed that 1.01 g ofpolypropylene per 1 g of the supported metallocene catalyst wassupported.

(3) Production of Propylene//propylene/1-butene Block Copolymer

A 1.5-L stainless autoclave equipped with a stirrer and purged withnitrogen was charged with 0.8 liter of a liquefied propylene and 1.0mmol of triethyl aluminum, and the mixture was stirred at 50° C. for 10minutes. 70.3 mg of the supported metallocene catalyst prepared in (2)above and 0.2 liter of a liquefied propylene were added, and whilekeeping the internal temperature of the autoclave at 50° C., thepolymerization was carried out for 35 minutes. After the polymerizationtime passed, unreacted propylene was discharged out of the system.

Subsequently, 0.5 mmol of triethyl aluminum was added to thepolymerization reactor, the temperature of the reactor was kept at 50°C., a propylene/1-butene mixed gas (molar ratio ofpropylene/1-butene=26/74) was fed to the reactor so as to keep thepressure of the reactor at 0.6 MPa, and the gas phase polymerization ofpropylene/1-butene was continued for 345 minutes. The supply of apropylene/1-butene mixed gas was stopped and unreactedpropylene/1-butene mixed gas was discharged out of the system. From thereactor, 264 g of the resulant propylene//propylene/1-butene blockcopolymer were recovered.

After completion of the polymerization, neither generation of thepolymer in lump within the opened reactor, i.e., reactor chunking, noradhesion of the polymer on the wall surface of the reactor, i.e.,reactor fouling was observed.

The recovered propylene//propylene/1-butene block copolymer had a1-butene content of 55% by weight, BD (bulk density) of 440 kg/m³, anintrinsic viscosity [η]_(W) of 1.15 dl/g, a melting point of 155° C. and64° C.

For the resultant propylene//propylene/1-butene block copolymer, it wascalculated that segment A was 32% by weight, segment B was 68% by weightand a 1-butene content in segment B was 81% by weight. Thepolymerization activity, ZY was calculated to be 1.8×10⁶ g·polymer/g·Zr.

The production of block copolymer was carried out three times in totalin the same manner as mentioned above, for evaluating the physicalproperties of the resultant block copolymers.

(4) Evaluation of Physical Properties of Propylene//propylene/1-buteneBlock Copolymer

0.05 part by weight oftetrakis[methylene(3,5-di-tert.butyl-4-hydroxyl.hydrocinnamate)]methane,0.1 part by weight of tris(2,4-di-tert.butyl-phenyl)phosphite and 0.05part by weight of calcium stearate, based on 100 parts by weight of theblock copolymer as prepared above, were mixed. The mixture waspelletized using a single screw extruder having a screw diameter of 15mm and set at an extrusion temperature of 190° C. to prepare a resincomposition containing the above block copolymer as a base resin. Aninjection molded article formed from the resin composition was evaluatedfor the physical properties. The result is shown in Table 3.

EXAMPLE 4

(1) Production of Propylene/1-butene//propylene/1-butene Random BlockCopolymer

A 1.5-L stainless autoclave equipped with a stirrer and purged withnitrogen was charged with 0.8 liter of a liquefied propylene/liquefied1-butene mixed monomer (molar ratio of propylene/1-butene=86/14) and 1.0mmol of triethyl aluminum, and the mixture was stirred at 40° C. for 10minutes. 95.3 mg of the supported metallocene catalyst prepared inExample 3(2) and 0.2 liter of a liquefied propylene/liquefied 1-butenemixed monomer (with the same molar ratio as mentioned above) were added,and while keeping the internal temperature of the autoclave at 40° C.,the polymerization was carried out for 40 minutes. Subsequently,unreacted mixed monomer was discharged out of the system.

Subsequently, 0.5 mmol of triethyl aluminum was added to thepolymerization reactor, the temperature of the reactor was kept at 50°C., a propylene/1-butene mixed gas (molar ratio ofpropylene/1-butene=27/73) was fed to the reactor so as to keep thepressure of, the reactor at 0.6 MPa, and the gas phase copolymerizationof propylene/1-butene was continued for 210 minutes. After thepolymerization time passed, the supply of a propylene/1-butene mixed gaswas stopped and unreacted propylene/1-butene mixed gas was dischargedout of the system. From the reactor, 336 g of the resultantpropylene/1-butene//propylene/1-butene random block copolymer wererecovered.

After completion of the polymerization, neither generation of thepolymer in lump within the opened reactor, i,e., reactor chunking, noradhesion of the polymer on the wall surface of the reactor, i.e.,reactor fouling was observed.

The recovered propylene/1-butene//propylene/1-butene random blockcopolymer had a 1-butene content of 56% by weight, RD (bulk density) of440 kg/m^(3,) an intrinsic viscosity [η]_(W) of 1.27 dl/g, a meltingpoint of 122° C. and 60° C.

For the resultant propylene/1-butene//propylene/1-butene random blockcopolymer, it was calculated that segment A was 29% by weight, segment Bwas 71% by weight, a 1-butene content in segment A was 14% by weight anda 1-butene content in segment B was 73% by weight. The polymerizationactivity, ZY was calculated to be 1.7×10⁶ g·polymer/g·Zr.

The production of block copolymer was carried out three times in totalin the same manner as mentioned above, for evaluating the physicalproperties of the resultant block copolymers.

(2) Evaluation of Physical Properties ofPropylene/1-butene//propylene/1-butene Random Block Copolymer

A resin composition containing the above block copolymer as a base resinwas prepared in the same manner as in Example 3, and an injection-moldedarticle formed therefrom was evaluated for the physical properties. Theresult is shown in Table 3.

Comparative Example 3

(1) Production of Propylene/1-butene Copolymer

A 50-L autoclave completely purged with nitrogen was charged with 20.8liters of n-hexane, 2.5 kg of 1-butene and 25 mmol of triisobutylaluminum, the temperature of the mixture was elevated to 70° C.,propylene was fed to provide a total pressure of 0.7 MPaG, and 25 mmolof triethyl aluminum and 0.125 mmol (in terms of Ti atom) of a titaniumcatalyst supported on magnesium chloride were added. While keeping thetotal pressure at 0.7 MPaG by continuously feeding propylene,polymerization was continued for 30 minutes. After the polymerization,the autoclave was vented and the polymer was recovered in a great amountof methanol and dried at 110° C. under reduced pressure for 12 hrs. Theresultant polymer was 840 g, a 1-butene content in the polymer was 31%by weight, and a melting point was 110° C.

(2) Evaluation of Physical Properties of Propylene/1-butene Copolymer

A resin composition containing the above propylene/1-butene copolymer asa base resin was prepared in the same manner as in Example 3, and aninjection-molded article formed therefrom was evaluated for the physicalproperties. The result is shown in Table 3.

Comparative Example 4

(1) Production of Propylene/1-butene Copolymer

A 1.5-L stainless autoclave equipped with a stirrer and purged withnitrogen was charged with 0.8 liter of a liquefied propylene/liquefied1-butene mixed monomer (molar ratio of propylene/1-butene =76/24) and1.0 mmol of triethyl aluminum, and the mixture was stirred at 40° C. for10 minutes. 52.1 mg of the supported metallocene catalyst prepared inExample 3(2) and 0.2 liter of a liquefied propylene/liquefied 1-butenemixed monomer (with the same molar ratio as mentioned above) were added,and while keeping the internal temperature of the autoclave at 40° C.,polymerization was carried out for 20 minutes. Subsequently, unreactedmixed monomer was discharged out of the system. 20 g of the polymer wasrecovered, but the recovered polymer was formed in lump. A 1-butenecontent in the polymer was 24% by weight.

Comparative Example 5

(1) Production of Propylene/ethylene Copolymer

A 1.5-L stainless autoclave equipped with a stirrer and purged withnitrogen was charged with 500 g of dried salt, and then with 2 mmol oftriisobutyl aluminum and 500 ml of a liquefied propylene, and themixture was stirred for 30 minutes. Subsequently, the liquefiedpropylene was discharged out of the system, and moisture adsorbed on thesalt was removed by a vacuum replacement. Subsequently, 1 mmol oftriisobutyl aluminum and 131 mg of the supported catalyst prepared inExample 3(2) were added, the mixture was kept at 30° C., apropylene/ethylene mixed monomer (molar ratio ofpropylene/ethylene=81.6/18.4) was fed to the polymerization reactor at arate of 5000 ml/min so that the pressure within the reactor was kept ata constant pressure of 1 MPaG, and a copolymerization ofpropylene/ethylene was performed. The recovered propylene/ethylenecopolymer was 76 g and bulk. An ethylene content in the polymer was 10%by weight.

In the production of the propylene//propylene/olefin block copolymers inthe presence of the olefin polymerization catalyst systems containingthe supported metallocene catalysts or preactivated catalysts accordingto the present invention, the production result exhibits the highpolymerization activity ZY, as shown above in Examples 1 and 2, ascompared with that using the supported metallocene catalyst orpreactivated catalyst of Comparative Examples 1 and 2. The resultantpropylene//propylene/olefin block copolymers have higher bulk densityBD. There was neither adhesion of the polymer to the polymerizationreactor, i.e., reactor fouling, nor generation of the polymer in lump,i.e., reactor chunking. They have very good particle morphology.Moreover, the amount of aluminoxane used is reduced. As shown inExamples 3 and 4, the specific copolymers have high BD, good particlemorphology, and also excellent impact resistance, stiffness andtransparency.

TABLE 1 Example Comparative Example 1 2 1 2 Supported Catalyst Step (a)Al/metallocene molar ratio 248 248 248 248 Reaction temperature (° C.)25 25 25 25 Reaction time (min) 5 5 5 5 Step (b) Amount of support (g)100 100 100 100 Contact temperature (° C.) 100 115 60 100 Contact time(hr) 1 1 1 1 Step (c) Separation process allowing allowing allowingallowing to stand to stand to stand to stand Washing solvent n-hexanei-pentane n-hexane toluene Total amount of washing solvent 10 10 10 10used (1) Washing temperature (° C.) −10 −5 −10 −10 Total number of timesof washing 5 5 5 5 (times) Supported catalyst Zr content (%) 0.61 0.580.44 0.16 Al content (%) 18.2 17.0 16.9 11.5 >350 μm agglomerate content(%) 0.0 0.0 0.0 0.0 Preactivated catalyst Step (e) Prepolymerizingolefin Pr — Pr Pr Prepolymerization temperature 0 — 0 0 (° C.) Feedingrate (mol/min) 0.15 — 0.15 0.15 Feeding time (min) 90 — 90 90Preactivated catalyst Olefin polymer Supported amount (g/g) 0.7 — 0.70.7 In the table, Pr stands for propylene. (−) shows the absence of step(e).

TABLE 2 Example Comparative Example 1 2 1 2 First polymerization step(A) Polymerization process gas phase bulk gas phase gas phase Olefin PrPr—Et Pr Pr Polymerization temperature (° C.) 50 50 50 50 Polymerizationpressure (MPa) 1.87 2.2 1.87 1.87 Polymerization time (hr) 2 2 2 2Segment A Et content (wt %) — 0.2 — — Intrinsic viscosity (dl/g) 1.451.41 1.40 1.30 Second polymerization step (B) Polymerization process gasphase gas phase gas phase gas phase Olefin Pr—Et Pr—Et Pr—Et PrPolymerization temperature (° C.) 50 50 50 50 Polymerization pressure(MPa) 1.6 1.6 1.6 1.6 Polymerization time (hr) 1 1 1 1 Segment B Etcontent (wt %) 58.9 62.3 64.9 67.8 Intrinsic viscosity (dl/g) 1.40 1.271.40 1.35 Results of whole copolymerization Polymerization activity (ZY)1.5 × 10⁶ 2.6 × 10⁶ 7.7 × 10⁵ 1.0 × 10⁶ (g/gZr) Generation of reactorchunking No No No No Generation of reactor fouling No No No No BlockCopolymer Segment A (wt %) 81 86 84.6 82 Segment B (wt %) 19 14 15.4 18Et content (wt %) 11.2 8.9 10.0 12.2 Intrinsic viscosity (dl/g) 1.441.39 1.40 1.31 Bulk density (BD) (kg/m³) 360 370 320 300 In the table,Pr stands for propylene and Et stands for ethylene.

TABLE 3 Comparative Example 3 Example 4 Example 3 MFR (g/10 min) 22 12 5Flexural modulus (MPa) 310 300 240 Izod impact strength, 25 25 10 0° C.(kJ/m²) Haze (%) 10 7 13

Industrial Applicability

The propylene//propylene/olefin block copolymers of the presentinvention are excellent in impact resistance, stiffness, transparencyand heat-sealing properties at low temperature, and can be used suitablyin the use application for which various characteristics are required.According to the present processes, the copolymers having good BD andparticle morphology can be produced efficiently.

What is claimed is:
 1. In a process of producing apropylene//propylene/olefin block copolymer which comprises 20-95% byweight of segment A comprising a polymer based on propylene and 80-5% byweight of segment B comprising a propylene/olefin random copolymer, saidprocess being carried out by the following steps (A) and (B) insequence: (A) a first polymerization step wherein propylene or a mixtureof propylene and olefin(s) other than propylene is polymerized in thepresence of a catalyst system for olefin polymerization comprising asupported metallocene catalyst and an organoaluminum compound, toproduce the segment A comprising a polymer based on propylene wherein aweight ratio of units of olefin(s) other than propylene/units ofpropylene in the polymer chain is from 0/100 to 30/70, and (B) a secondpolymerization step wherein a mixture of propylene and olefin(s) otherthan propylene is copolymerized in the presence of the polymer based onpropylene containing the catalyst system for olefin polymerization fromthe first polymerization step, to produce the segment B comprising thepropylene/olefin random copolymer wherein a weight ratio of units ofpropylene/units of olefin(s) other than propylene in the polymer chainis from 5/95 to 95/5, the improvement comprising the supportedmetallocene catalyst being prepared by carrying out in sequence thefollowing steps of: (a) reacting an aluminoxane with an organictransition metal compound having two π-electron conjugated ligandscrosslinked each other in an inert solvent, (b) contacting a reactionproduct formed in step (a) with an inorganic finely particulate supportin an inert solvent at a temperature of 85-150° C., and (c) washing atleast two times a slurry containing the solid product formed in step (b)with an aliphatic hydrocarbon at a temperature of −50 to 50° C. toprepare the supported metallocene catalyst.
 2. The process of producingthe propylene//propylene/olefin block copolymer set forth in claim 1,characterized in that a weight ratio of units of other olefin(s) thanpropylene/units of propylene in the polymer based on propylene producedin the first polymerization step is from 0/100 to 10/90.
 3. The processset forth in claim 1 wherein the supported metallocene catalyst contains0.01-5% by weight of a transition metal derived from an organictransition metal compound and 0.1-50% by weight of aluminum derived fromaluminoxane.
 4. The process set forth in claim 1 wherein the inorganicfinely particulate support has an average particle size of 5-300 μm. 5.The process set forth in claim 1 wherein the inert solvent is anaromatic hydrocarbon.
 6. The process set forth in claim 1 wherein thealiphatic hydrocarbon is n-hexane or isopentane.
 7. In a process ofproducing a propylene//propylene/olefin block copolymer which comprises20-95% by weight of segment A comprising a polymer based on propyleneand 80-5% by weight of segment B comprising a propylene/olefin randomcopolymer, said process being carried out by the following steps (A) and(B) in sequence: (A) a first polymerization step wherein propylene aloneor a mixture of propylene and olefin(s) other than propylene ispolymerized in the presence of a catalyst system for olefinpolymerization comprising a granular preactivated catalyst and anorganoaluminum compound, to produce the segment A comprising a polymerbased on propylene wherein a weight ratio of units of olefin(s) otherthan propylene/units of propylene in the polymer chain is from 0/100 to30/70, and (B) a second polymerization step wherein a mixture ofpropylene and olefin(s) other than propylene is copolymerized in thepresence of the polymer based on propylene containing the catalystsystem for olefin polymerization from the first polymerization step, toproduce the segment B comprising the propylene/olefin random copolymerwherein a weight ratio of units of propylene/units of olefin(s) otherthan propylene in the polymer chain is from 5/95 to 95/5, theimprovement comprising the granular preactivated catalyst being preparedby carrying out in sequence the following steps of: (a) reacting analuminoxane with an organic transition metal compound having twoπ-electron conjugated ligands crosslinked each other in an inertsolvent, (b) contacting a reaction product formed in step (a) with aninorganic finely particulate support in an inert solvent at atemperature of 85-150° C., (c) washing at least two times a slurrycontaining the solid product formed in step (b) with an aliphatichydrocarbon at a temperature of −50 to 50° C., to prepare a supportedmetallocene catalyst, and (d) contacting the supported metallocenecatalyst prepared in step (c) with an olefin to prepolymerize the olefinand to form the granular preactivated catalyst, whereby 0.01-100 kg ofthe olefin prepolymer per kg of the supported metallocene catalyst isfurther supported on the supported metallocene catalyst.
 8. The processof producing the propylene//propylene/olefin block copolymer set forthin claim 7, characterized in that a weight ratio of units of otherolefin(s) than propylene/units of propylene in the polymer based onpropylene produced in the first polymerization step is from 0/100 to10/90.
 9. The process set forth in claim 7 wherein the supportedmetallocene catalyst contains 0.01-5% by weight of a transition metalderived from an organic transition metal compound and 0.1-50% by weightof aluminum derived from aluminoxane.
 10. The process set forth in claim7 wherein the inorganic finely particulate support has an averageparticle size of 5-300 μm.
 11. The process set forth in claim 7 whereinthe inert solvent is an aromatic hydrocarbon.
 12. The process set forthin claim 7 wherein the aliphatic hydrocarbon is n-hexane or isopentane.13. The process set forth in claim 7 wherein an contact of the supportedmetallocene catalyst with an olefin in step (d) is performed byintroducing an olefin into a slurry of the supported metallocenecatalyst prepared in step (c) and dispersed in an aliphatic hydrocarbon.14. The process set forth in claim 7 wherein the olefin to beprepolymerized is selected from ethylene, propylene, 3-methyl-1-buteneand the mixture thereof.
 15. A propylene//propylene/olefin blockcopolymer which comprises 20-95% by weight of segment A comprising apolymer based on propylene and 80-5% by weight of segment B comprising apropylene/olefin random copolymer, and which is obtainable by carryingout in sequence the following steps (A) and (B): (A) a firstpolymerization step wherein propylene alone or a mixture of propyleneand other olefin(s) than propylene is polymerized in the presence of acatalyst system for olefin polymerization comprising a supportedmetallocene catalyst and an organoaluminum compound, to produce thesegment A comprising a polymer based on propylene wherein a weight ratioof units of other olefin(s) than propylene/units of propylene in thepolymer chain is from 0/100 to 30/70, and (B) a second polymerizationstep wherein a mixture of propylene and other olefin(s) than propyleneis copolymerized in the presence of the polymer based on propylenecontaining the catalyst system for olefin polymerization from the firstpolymerization step, to produce the segment B comprising thepropylene/olefin random copolymer wherein a weight ratio of units ofpropylene/units of other olefin(s) than propylene in the polymer chainis from 5/95 to 95/5, the supported metallocene catalyst being preparedby carrying out in sequence the following steps of: (a) reacting analuminoxane with an organic transition metal compound having twoπ-electron conjugated ligands crosslinked each other in an inertsolvent, (b) contacting a reaction product formed in step (a) with aninorganic finely particulate support in an inert solvent at atemperature of 85-150° C., and (c) washing at least two times a slurrycontaining the solid product formed in step (b) with an aliphatichydrocarbon at a temperature of −50 to 50° C.
 16. Thepropylene//propylene/olefin block copolymer set forth in claim 15,characterized in that a weight ratio of units of other olefin(s) thanpropylene/units of propylene in the polymer based on propylene producedin the first polymerization step is from 0/100 to 10/90.